\-yourplugin/ {plugin-root}  
 -yourplugin.css {essential CSS}  
 -yourplugin_debug.css {CSS for debugging} 
 -yourplugin_doc.html {Examples and Explanation}  
 -yourplugin_skins.css {all skins that only require pure css, others via @import}  
 -\ skins/ {skins that need more than pure CSS, eg. images}  
   -\ photo/ {skin-root}  
     -photo_skin.css  
     -img/  
   -\ flow/ {skin-root}  
     -flow_skin.css  
     -img/